Means for refrigeration



April 4, 1944. F. R. BICHOWSKY 2,345,651

MEANS FOR REFRIGERATION Filed June 28, 1941 fl it 35- 14 lllllllllllllllllllilllllllllllllllllll Z6 55-5 M; M

INVENTOR Patented Apr. 4, 1944 UNITED STATES PATENT OFFICE MEANS FOR REFRIGERATION Francis E. Bichowsky, Detroit, Mich.

Application June 28, 1941, Serial No. 400,242

1 Claim.

The present invention relates to methods and means for refrigerating and air conditioning. It is more particularly concerned with such methods and means utilized in conjunction with or as a part or function of vacuum absorption apparatus.

In air conditioning enclosures it has been found that the use of vacuum absorption apparatus for cooling has certain advantages. For example, very high thermal efilciencies relative to those of the compression and inert gas type of apparatus are obtained. However, certain practical disadvantages are encountered since there has not heretofore been available any simple means for circulating the absorbent and refrigerant, and for maintaining proper pressure differentials between various parts of the system. Thus, in the known practice, a pump is introduced into the circuit to produce proper and adequate circulation of the fluids therein, and in my prior application, Serial No. 286,989, filed July 28, 1939, a pumpless system is disclosed and claimed wherein by the relative positioning of the various parts of the system, fluids are induced to flow throughout the system by means of differences in pressure and differences in density in these various parts.

The present invention comprehends an improvement upon this system whereby more effective and rapid circulation of fluids is obtained without the use of a mechanical pump.

It is, therefore, a principal object of the present invention to provide an efficient method and a compact apparatus for air conditioning or refrigerating by means of a vacuum absorption circuit utilizing novel fluid circulation means. Other objects include providing means for controlling air conditioning apparatus which are responsive to both the temperature and the humidity of the enclosure to be conditioned, and also providing vacuum absorption apparatus having an aircooled absorber and an evaporator which may be utilized for the direct cooling of air.

The invention may be explained in detail with reference to the accompanying drawing, in which:

Fig. 1 is a diagrammatic view of a refrigeration apparatus utilizing the principle of the present invention;

Fig. 2is a diagrammatic view of apparatus similar to that shown in Fig. 1 adapted for air conditioning in conjunction with a secondary refrigerant.

In Fig. 1, a portion of a refrigerator cabinet I is shown containing the evaporator utilized in the present apparatus. The evaporator II is positioned in the upper portion of the refrigerator cabinet and is designed so that a space I2, surrounded by the evaporator, is provided to contain trays for ice cubes or other material to be cooled. Provided in the upper horizontal surface of theevaporator II is a refrigerant input line l3 and extending from the lower vertical face of the evaporator l| adjacent the rest of the apparatus is a refrigerant outlet opening l4 into the upper portion of the absorber chamber l5.

The absorber I5 is shown positioned adjacent to and at a lower level than the evaporator A used absorbent outlet line l6 opens from the floor of the absorber l5 and an absorbent inlet line l'l opens into a distributing device, such as spray heads H3, in the upper portion thereof. Leading from the side of the absorber l5 and opening into the top of the evaporator H is a booster fluid line I9 for passing booster fluid vapor to the evaporator II, as hereinafter more fully explained. Condensed booster fluid is passed fromthe evaporator II to the previously mentioned absorbent outlet line It from the ab sorber l5 by a passage opening from the floor of the evaporator into said line It.

chamber 2| to the regenerator 26.

The absorbent outlet line Hi from the absorber l5 opens into a contact chamber 2|, which is provided with a vapor lifgtube 22. Leading into the side of the contact chamber 2| are two lines. a regenerated absorbent input line 23 and a booster fluid input line 24. An outlet line 25 leads from the bottom of the contact chamber 2| and opens into a regenerator chamber 26.

The regenerator chamber 26 is equipped with a vapor lift tube 21 in the top and a heating means 28. The vapor lift tube 2'! leads into the bottom of an analyzing chamber 29, from the top of which a vapor line 30 leads to a condenser 3| from whence it connects with the previously mentioned refrigerant input line Hi to the evaporator passing through a cooling coil in heat exchange relation to the interior of the evaporator prior to being led thereinto. From the side of the analyzer 29, as shown, an absorbent line 23 passes to the absorbent input in the contact chamber 2| heretofore described. This line may, if desired, be placed in thermal communication with the absorbent line 25 through which absorbent to be regenerated passes from the contact The vapor lift tube 22 leading from the topof the contact chamber 2| goes into a separating chamber 32. Vapor is passed from said separating chamber 32 by a booster fluid line 33 leading out of the top of the separating chamber to a booster fluid condenser 34 at a higher level and back to the booster fluid input line 24 in the contact chamber 2|. Liquid separated from vapor in the separating chamber 32 is passed to the distributing device l8in the absorber I! by the: absorbent inlet line H which leads from the lower side of the contact chamber mentioned in the description of the absorber.

It can now be seen that this system contains three complete circuits which are in part coin-' cidental. The circuits are the refrigerant circuit, the absorbent circuit, and the booster fluid circuit. The refrigerant circuit carries refrigerant from the evaporator into the absorber I where the refrigerant and absorbent circuit become one. The refrigerant-absorbent circuit then passes to the contact chamber 2|, from thence to the regenerator 26, and to the analyzer 29, where the circuits separate to go heir individual ways, the refrigerant circuit lea ng to the condenser 3| and back to the evaporator ll, while the absorbent circuit passes back to the contact chamber 2|, into the separating'chamber 32, and to the absorber IS. The third circuit, wherein the booster fluid circulates, is coincidental with the absorbent circuit in the contact chamber 2| and from the contact chamber into the separating chamber 32. From the separating chamber the booster fluid circuit leads individually to the booster fluid condenser-34 and back to the contact chamber 2|.

tact chamber 2| and then is circulated by the vapor lift tube 22 to the separating chamber :2 and thence back to the absorber l5 by the action of the booster fluid, which latter is now to be de-- scribed. This fluid, which enters the contactchamber 2| by the inlet 24, should be substan tially insoluble in the absorbent solution, should be a fluid which is in the liquid phase at room temperature under the pressure existing in the system at such a temperature, and should have a boiling point under the pressure in the apparatus which is below that of the absorbent solution and below the temperature at which the absorbent solution enters the contact chamber. It is likewise necessary that the material be stable to heat at the temperatures and pressures encountered in use. It has been generally found that the aforementioned boiling point of this booster fluid should fall between 30 and 50 C. under 10 millimeters of mercury pressure. Among the fluids which fulfill the aforementioned requirements and are satisfactory for use in a vacuum absorption system as booster fluids are normal nonane and propyl benzene.

Such a booster fluid upon entering the contact chamber is vaporized therein since it is entering a medium having a temperature above its boiling point at that pressure. The expanding of the booster fluid upon vaporization makes it necessary for some of the material in the contact chamber to escape therefrom to allow for the in- In the operation of the apparatus shown in Fig. lto cool thecabinet, the evaporator is evacuated and a refrigerant entering by the refrigerant input line I3 is evaporated in the evaporator vapor carried into the absorber l5 through the refrigerant passage H. In the absorberl5, en.. tering from the regenerator 26, a liquid absorbent such as an aqueous solution of zinc chloride or lithium chloride is sprayed by the distributing device |8 so as to expose a large surface area of absorbent to the incoming refrigerant vapor. This refrigerant vapor is taken up or absorbed by the absorbent and the resulting solution passed to the contact chamber 2| through the absorbent outlet line i6 leading from the absorber. From the contact chamber 2| the absorbent-refrigerant mixture is in part circulated by gravity to the regenerator 26, the remainder being recycled to the absorber l5, as more fully described hereinafter.

The absorbent-refrigerant mixture entering the regenerator 26 is subjected to heat in said re,- generator in sumcient quantity to vaporize the refrigerant, whereupon the refrigerant vapor and absorbent liquid entrained therein pass from the vapor lift tube 21 in the top of the regenerator 26 to the analyzer 29. In this latter chamber, the absorbent separates from the mixture, liquid absorbent being returned to the contact chamber 2| by the line 23 leading from the side of the analyzer 29, while the refrigerant vapor continues from the top of the analyzer 29 by the passage 30 to the condenser 3| through a mercury filled tube, and thence as liquid to the evaporator for re-utiiization, being pre-cooled' prior to entering the evaporator l in the cooling coil section of the return line 35, which passes through the interior of the evaporator I, thus placing the concreased volume. This overflow is taken care of by the vapor lift tube 22. The vapor of the booster fluid, carrying slugs of entrained absorbent, passes up this tube to a separating chamber 32, where the vapor and liquid separate, the vapor continuing on up to the booster fluid condenser 34, where it is condensed and returned to the contact chamber 2|, while the absorbent is passed to the absorbent distributor l8 in the absorber l5.

In actual operation of this system a small amount of the booster fluid may be carried into the absorber being entrained in the returning absorbent. However, since the temperature in the absorber is such that the booster fluid is above its boiling point at the pressure existing therein, booster fluid vaporized in the absorber is passed to the evaporator II by the booster fluid line l9 leading from the absorber 5 to the evaporator l I. If now the booster fluid has been selected from a group of materials which have the previously mentioned boiling point and solubility characteristics, and, in addition thereto, are condensed at the temperature and pressure in the evaporator II, this vapor passed from the absorber l5 to the evaporator II will be condensed in the latter chamber. This condensate is then returned to the absorber l5 through the passage 20 opening from the floor of the evaporator I so that it may be again vaporized and passed to the evaporator I or enter the absorbent line l6 leading from the absorber I5 to the contact chamber 2|.

In Fig. 2 is shown a modification of the apparatus illustrated in Fig. 1' adapted for use in conditioning air. Repla cingthe space for ice cube refrigerant line so that the secondar'y refrigerant may be short-circuited under certain conditions, past the heat exchange coil 53, and returned to the evaporator. A valve 55 is placed in the secondary refrigerant line 52 leading to the heat exchange coil, the operation of which is controlled by a thermostat 56 located in the space, while a second valve 51 operated by a humidostat 58 located in the space is placed in the by-pass line 54 to control the passage of liquid therethrough.

Air from the space to be conditioned is drawn in through the opening shown 59 adjacent the wall, passed over the secondary refrigerant heat exchange coil 53 and returned to the space. Since, from time to time it is usually found desirable to add fresh air to this re-circulated air and discharge a portion of the used air to waste, a damper 60 is placed in the wall for admitting such fresh air. This damper is operated by a float valve 6| the float therefor being in a sump 52 placed below the heat exchange coil 53 to collect the condensate therefrom which results from the contact of the air with the cold surface. The general effect of this system in operation is to admit increased amounts of fresh air as the amount of moisture condensed from the air rises. Thus, as the population of the room is increased, the humidity will rise and more fresh air will be added to care for the increased reqpirements. A calibrated orifice 63 is positioned in the floor of the sump 62 so that in discharging condensate to waste, the head of liquid in the sump is proportional to the rate of condensation.

The operation of the valves 55, 51 under the c'mtrol of the humidostat 58 and the thermostat L6 is, in the case of the humidostat 56, to close the by-pass valve 51, thus decreasing the temperature of secondary refrigerant passed to the heat exchange coil 53 when the humidity in the enclosure rises above a predetermined value. This decreased temperature condenses more moisture from the air until the humidity of the enclosure is again decreased to below the desired value, whereupon the by-pass valve 51 is again opened by the humidostat 58. The thermostat 55 operates a valve 55. When the temperature of the room decreases beyond a predetermined point, the thermostat 56 decreases the flow of secondary refrigerant in the line 52 thence decreases the total amount of cooling until the temperature again rises beyond the predetermined point when the secondary refrigerant flow is increased. This cooperative control of secondary refrigerant flow by the humidity and tem. perature in the enclosureresults in a substantially constant wet-bulb temperature therein whereby comfort is afforded the occupants at all times.

The apparatus shown in Fig. 1 differs from that in Fig. 2 in that the absorber 54 is air-cooled taking the general form of a calandrla evaporator whereby a cooling fluid, such as air, may be passed through the interior thus removing the heat of condensation of the refrigerant from the evaporator dissolving in the absorbent.

Also shown in the circuits of Fig. 2 is an input line 65 leading from the liquid tube H on the booster circuit into the absorber 64, thus making it possible to pass a desirable amount of booster fluid from the booster circuit into the absorbent circuit and thus obtain an increase in vapor circulation between the absorber and the evaporator resulting from the flow of booster fluid condensate between the two chambers. An outlet 61 for booster fluid from the refrigerant circuit is shown leading from a gooseneck 35 in the tube l3 leading from the refrigerant condenser 3| into the evaporator l I. This outlet leads into the bottom of the absorber. An opening 66 between the absorber and the evaporator provides means for passing the booster fluid vapor from the absorber into the evaporator wherein it condenses as explained in relation to Fig. 1 and passes bythe tube 20 leading from the bottom of the evaporator to the absorbent outlet line it from the absorber leading to the contact chamber.

Among the absorbents found to be satisfactory for use in this system are relatively concentrated aqueous solutions of lithium chloride, lithium bromide, zinc chloride, and the like.

Among the refrigerants found satisfactory are water, and dilute aqueous solutions of the abovementioned absorbents.

Among the advantages obtained by the use of the apparatus shown in the drawing is that close spacing of the secondary refrigerant tubes in the evaporator and provision of fins thereon increases the eificiency of the apparatus since refrigerant entering the evaporator from the condenser tends in part to spray into fine droplets without evaporating and to pass through the evaporator without abstracting any heat. If, as shown, this spray is collected on the surface of the secondary refrigerant carrying passage, it is evaporated therefrom thus evaporating in direct thermal communication with the secondary refrigerant and obtaining the utmost efliciency. Furthermore, if the fins are specially treated they may become more wettable thus providing a more effective surface for spreading liquid.

This treatment may take several forms, as a brass surface which has been heated in high vacuum to a temperature near the melting point at which the zinc distills out, or treating the surface of a copper alloy with an aqueous solution of bromide ion. Such treatment produces a surface having sub-microscopic pores of molecular dimension which aid greatly in securing the most effective use of the primary refrigerant.

I claim:

In a vacuum absorption system comprising an evaporator for the refrigerant, an absorber communicating therewith for dissolving refrigerant vapor in a liquid absorbent medium, a regenerator in communication with said absorber wherein the absorbent is freed of said dissolved refrigerant, a heater for the regenerator, and a condenser for refrigerant vapors in communication with the regenerator and the evaporator: means for returning the absorbent from the regenerator to the absorber comprising a booster circuit coincidental in part with an absorbent return line to the absorber, the portion of said booster circuit which is coincidental with the regenerator-absorber line constituting a contact zone wherein absorbent liquid and a condensible booster fluid insoluble therein are contacted, means for separating liquid absorbent from the booster fluid at a higher level than the contact chamber, means for returning the separated absorbent to the absorber, and means for condensing booster fluid outside the contact zone and returning it thereto.

FRANCIS R. BICHOWSKY. 

